This patent deals with a unique assembly of nozzles that shroud the propeller along with creating Venturi ports which adds water to the column filling in propeller disruptions, and increases the gallons per minute volume at the column discharge. Therefore, this patent deals with a unique multiple nozzle system that both shrouds the propeller and creates Venturi effects ports which direct propeller thrust, substantially improving the performance of the watercraft. By concentrating the thrust in a nozzle type of operation, the maneuverability and stability of the watercraft is greatly enhanced. Abrupt turns are possible because when the motor is turned the propeller is not sliding sideways, churning the water (cavitation), instead it is putting out a direct thrust in the desired direction. The stability is improved because the up and down movement or porpoising of the watercraft is minimized due to the direct flow of the water through the propeller nozzle assembly and the resistance to an up and down movement through the water by the assembly shrouds hydrodynamic configuration.
The inventor, possessing U.S. Pat. No. 4,637,801 Thrust Enhancing Propeller Duct Assembly for Watercraft, and U.S. Pat. No. 6,475,045 Thrust Enhancing Propeller Guard Assembly, has endeavored in this patent to refine his device making it function for large watercraft along with improving the mounting brackets, structural members and reinforcing the lower member to protect the skeg on outboard and inboard-outboard motors. Most outboard motors and many inboard-outboard have a fin type of protrusion below the propeller housing called the skeg which is the first thing on the motor to hit obstacles in the water. The inventors' endeavors in the field of watercraft propeller guards, includes the Kort Nozzle that is known worldwide. Additional patents issued to inventors endeavoring to create propeller guards are as follows:
U.S. Pat. No. 4,957,459 of Richard H. Snyder describes a marine drive propeller shroud with a cage having an internal spoke structure and a retainer structure mounting the cage to the gear case and engaging the gear case and drive shaft housing in a particular manner such that impact on the cage is transmitted to the junction of the lower skeg and the torpedo-shaped portion of the gear case, the leading edge of the gear case at the front edge the strut portion and the front edge of the skeg, the underside of the anti-cavitation plate and the rearwardly extending portion of the drive shaft housing above the cavitation plate and the splash plate.
This patent describes a conventional wire frame propeller guard that endeavors to add some protection to the skeg area of the motor, but greatly restricts the water flow past the torpedo-shaped gear case minimizing the output of the motor and greatly affecting the maneuverability of the watercraft. These styles of propeller guards have a tendency to churn the water around the propeller creating air bubbles and hampering the designed smooth water flow past the propeller.
U.S. Pat. No. 5,066,254 of Joseph D. Bass et al. describes a propeller guard primarily for the protection of the manatee but is also useful in the protection against injury to other animals and larger fish which might come in contact with a boat's propellers. This guard is tapered substantially toward a point at the front and is substantially circular at the rear end to encircle the region in which the propeller is rotated. The guard has a V-bracket at the front, which is securely pressed against a propeller support and is supported at the rear in the circular portion by a pair of clamps that engage and are bolted tightly onto the anti-cavitation plate.
This patent describes another simpler configuration of a wire frame propeller guard offering limited protection to the skeg, but still restricts water flow past the propeller and hampers the maneuverability of the watercraft.
U.S. Pat. No. 5,009,620 of Louis Feranda, Sr. describes a propeller guard that is provided with replaceable ribs that form a cage placed around the propeller of an outboard marine propulsion unit. The ribs are suspended from a flat upper plate bolted to the cavitation plate above the propeller. The ribs are maintained in spaced relation to each other around the propeller by the support plate and a longitudinally extending bottom bar bolted at one end to the skeg of the propulsion unit. In the event of damage to any of the ribs of the cage, the damaged rib can easily be replaced with a new one.
This patent describes still another wire frame or rib style of configuration with the advantage of replacing separate ribs when they are damaged. This guard offers no protection to the skeg area of the motor and still restricts water flow past the propeller and hampers the maneuverability of the watercraft. Again, these styles of propeller guards have a tendency to churn the water around the propeller creating air bubbles hampering the designed smooth water flow past the propeller.
U.S. Pat. No. 5,928,042 of James Quiggins describes a propeller guard for use in association with a boat propulsion propeller driven by an outboard motor or an inboard-outboard rear motor drive unit. The propeller guard may be constructed of injection molded plastic, fiber reinforced resin, metal such as aluminum or other materials having strength characteristics to provide necessary protection and constructed to minimize hydrodynamic resistance. The propeller guard will protect swimmers, aquatic mammals and other sea life from coming into contact with the propeller thereby preventing injury and at the same time protect the propeller from damage by engagement with floating or submerged debris.
This patent describes a propeller guard using flat configuration to minimize the hydrodynamic resistance, but does not eliminate it or does not attempt to direct the water flow into the area of the propeller. This propeller guard also offers no protection to the area of the skeg of the motor.
U.S. Pat. No. 5,975,969 of John Forrest White describes a hydrofoil propeller guard, including a thrust tube, a hydrofoil fin and bottom securing plate. This device is used in conjunction with an outboard motor mounted on a boat with stern drives, to encompass the propeller to reduce sideways thrust, to move items away from the propeller, and the guard preferably includes a trolling plate to increase slow speed performance.
This patent describes a hydrofoil propeller guard with a single thrust tube with the flat sides parallel to the centerline of the propeller shaft. This design incorporates the conventional hydrofoil and allows for minimum drag but does not direct the water flow towards the propeller and does not reinforce the area of the skeg. If debris is directed into the area of the propeller, there is a relatively large area where it may enter and in doing so can knock the thrust tube into the propeller.
None of the foregoing prior art teaches or suggests the particular unique features of the propeller nozzle assembly and thus clarifies the need for further improvements in the safety devices used on watercraft.